pnfs_nfs: fix _cancel_empty_pagelist

Orabug: 25308027

[ Upstream commit 5e3a98883e7ebdd1440f829a9e9dd5c3d2c5903b ]

pnfs_generic_commit_cancel_empty_pagelist calls nfs_commitdata_release,
but that is wrong: nfs_commitdata_release puts the open context, something
that isn't valid until nfs_init_commit is called, which is never the case
when pnfs_generic_commit_cancel_empty_pagelist is called.

This was introduced in "nfs: avoid race that crashes nfs_init_commit".

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit eba391c749fe8a47aea9de2e78fadc02434b5417)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>

diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 8bd645a1913ba70821b81739532d3045457e12db..19c1bcf70e3e879707e8194aa51caa3bfa6e637b 100644 (file)
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -247,7 +247,11 @@ void pnfs_fetch_commit_bucket_list(struct list_head *pages,
 }
 
 /* Helper function for pnfs_generic_commit_pagelist to catch an empty
- * page list. This can happen when two commits race. */
+ * page list. This can happen when two commits race.
+ *
+ * This must be called instead of nfs_init_commit - call one or the other, but
+ * not both!
+ */
 static bool
 pnfs_generic_commit_cancel_empty_pagelist(struct list_head *pages,
                                          struct nfs_commit_data *data,
@@ -256,7 +260,11 @@ pnfs_generic_commit_cancel_empty_pagelist(struct list_head *pages,
        if (list_empty(pages)) {
                if (atomic_dec_and_test(&cinfo->mds->rpcs_out))
                        wake_up_atomic_t(&cinfo->mds->rpcs_out);
-               nfs_commitdata_release(data);
+               /* don't call nfs_commitdata_release - it tries to put
+                * the open_context which is not acquired until nfs_init_commit
+                * which has not been called on @data */
+               WARN_ON_ONCE(data->context);
+               nfs_commit_free(data);
                return true;
        }